Holocene mean temperatures derived from beetle studies in

Holocene mean
temperatures derived
from beetle studies in
the Abisko area, N
Sweden
Geoffrey.lemdahl@lnu.se
Phil.Buckland@arke.ume.se
Fredrik.Olsson@arke.ume.se
This lecture
• Insects respons to climate change
• Mutual Climatic Range method
(MCR)
• Holocene MCR data from Lake
Tibetanus, Abisko, N Sweden
• Other climate records from the
same area
Green tiger beetle
(Cicindela campestris)
• Larvae and adults are exclusively
carnivorous generalists
• Cold-blooded
• Habitat: sandy ground with sparse
vegetation
• Open, warm, sun exposed
environments
Insects and climate
• Climate often limits insects
geographical distribution
• Arctic to temperate areas
– Temperatures sets the limits
• Stenothermic species
– Species adapted to a narrow
temperature span
Where are insect
remains found?
Ca 5000 year old insect remains in peat from a bog in
Småland
• Preserve well in wet/moist
environments
• Natural deposits
• lake and fluvial sediments
• Carr and bog peat
Beetles
(Coleoptera)
• Robust exoskeleton
– Body parts of adults
– Identification to species level
• Diverse adaption to both terrestrial and
aquatic habitats
• Many stenothermic species
– Predators, scavengers genaralists
Climate reconstructions
• Mean temperature
reconstructions
– Mutual Climatic Range method
(MCR)
• Mean temperature of the warmest
month (TMAX)
• Mean temperature of the coldest
month (TMIN)
• Difference summer/winter
temperatures (TRANGE)
• Changes in humidity
Geographical distribution
→ Climatic range
• Atkinson et al.
1987. Nature
352:587-592
• Data from
metereological
stations
• Geographical
space is
translated to
temperature
range
• Climate
envelopes for
each species
• Data base of
climate envelopes
Elias 2007
Climate envelopes
Elias 2007
• Stenothermic beetle species recorded in
a sample
• Envelopes stacked
• Overlapping range represent the
temperature reconstruction
• This is the climate range were all species
may coexist
MCR results
• Tests on modern beetle
assemblages adjacent to
weather stations
– Acceptable accuracy of
reconstructed temperatures
• Slight underestimation of Tmax and
Tmin of the coldest temperatures
• Regression equations
– Calibration of mean values
• Jack knife method
Abisko
Lake Tibetanus 560 m a.s.l.
Lake Njulla 999 m a.s.l.
Barnekow 1999
MCR results from Lake
Tibetanus
Macroscopic plant
remains from L Tibetanus
Barnekow, L. 1999. The Holocene 9:253-265
Barnekow 1999
Lake Njulla
999 m a.s.l.
• Diatom assemblages (July temp)
• Chironomid assemblages July temp
Bigler et al. 2003. J of Paleolimnology 23:13-29.